A chair of this type is known from Finnish Patent Specification Nos. 67,174 and 43,460. Similar chairs are also disclosed in U.S. Patent Specification Nos. 2,617,471 and 2,767,773 and Norwegian Patent Specification No. 104,303. These prior chairs are adjustable in such a way that a person who sits in the chair is able to assume a normal sitting position and at least one other position in which the person is more or less in a lying position with the calves more or less raised and directed forwards. Chairs according to the prior art do not enable a normal sitting position to be altered continuously and easily into a partly lying or a lying position with a possibility of locking all positions between these positions and in such a way that when being adjusted, the chair possesses an adjustable resistance to motion so that persons of different size and weight can easily change the movement characteristic of the chair as desired, which is important in order that the chair would function in a way expected from chairs of this type.